9. A salvage boat uses its winch to pull up a sunken treasure with an upward force of 4000 N. The mass of the treasure is 200 kg and the water exerts a force of 1500 N on the treasure, resisting the force exerted by the winch . The boat is directly above the treasure. Draw a free-body diagram for the treasure , calculate the acceleration , and predict the time dependence of the motion of the treasure, initially at rest.

area of focus

i think it would be 5

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.